Vacuum flange

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A KF-25 tee, o-ring, and clamp.
A KF-25 tee, o-ring, and clamp.

A vacuum flange is a flange at the end of a tube used to connect vacuum chambers, tubing and vacuum pumps to each other.

Contents

[edit] Vacuum flange types

A CF (conflat) pipe and flange with copper gasket.
A CF (conflat) pipe and flange with copper gasket.

Several vacuum flange standards exist, and the same flange types are called by different names by different manufacturers and standards organizations.

[edit] KF/QF

The ISO standard quick release flange is known by the names Quick Flange (QF), Klein Flange (KF) or NW, sometimes also as DN.[1] The KF designation has been adopted by ISO, DIN, and Pneurop. KF flanges are made with a chamferred back surface that attached with a circular clamp and an elastomeric o-ring that is mounted in a metal centering ring. Standard sizes are indicated by the nominal inner diameter in millimeters for flanges 16 through 50 mm in diameter.[2]

  • DN16KF
  • DN25KF
  • DN40KF
  • DN50KF

[edit] ISO

The ISO large flange standard is known as LF, LFB, MF or sometimes just ISO flange. As in KF-flanges, the flanges are joined by a centering ring and an elastomeric o-ring. An extra spring-loaded circular clamp is often used around the large diameter o-rings to prevent them from rolling off from the centering ring during mounting.

The ISO large flanges come in two varieties. The ISO-K (or ISO LF) flanges are joined with double claw clamps which clamp to a circular groove on the tubing side of the flange. The ISO-F (or ISO LFB) flanges have holes for attaching the two flanges with bolts. Two tubes with ISO-K and ISO-F flanges can be joined together by clamping the ISO-K side with single claw clamps which are then bolted to the holes on the ISO-F side.

ISO large flanges are available in sizes from 63 to 500 mm nominal tube diameter)[2].

  • DN63LF (63.5 mm)
  • DN100LF (102 mm)
  • DN160LF (160 mm)
  • DN200LF (200 mm)
  • DN250LF (254 mm)
  • DN320LF (316 mm)
  • DN400LF (400 mm)
  • DN500LF (500 mm)

[edit] CF

For ultra-high vacuum applications, there are ConFlat (CF) flanges that use a copper gasket and knife-edge flange to achieve the vacuum seal.[3] Conflat flanges operate down to 10-13 torr (10-11 Pa) pressure and can be heated to 450 °C for bake-out. North American flange sizes are given by flange outer diameter in inches: 1⅓ ("mini"), 2¾, 4½, 6, 8, 10, 12, 13¼, 14 and 16½. In Europe and Asia, sizes are given by tube inner diameter in millimeters:

  • DN16
  • DN40
  • DN63
  • DN100
  • DN160
  • DN200
  • DN250
A 60 kV high voltage electrical feedthrough on a 4-1/2 inch conflat flange
A 60 kV high voltage electrical feedthrough on a 4-1/2 inch conflat flange

[edit] Wheeler

A Wheeler flange is a large wire seal flange often used on large vacuum chambers.[4]

[edit] ASA

ANSI has a flange standard called ASA.[5] These flanges are elastomeric o-ring seal and can be used for both vacuum and pressure applications. Flange sizes are indicated by tube nominal inner diameter or by flange outer diameter (in inches): 1 (4.25 O.D.), 1.5 (5.00 O.D.), 2 (6.00 O.D.), 3 (7.50 O.D.), 4 (9.00 O.D.), 6 (11.00 O.D.), 8 (13.5 O.D.), 10 (16.00 O.D.).

[edit] Vacuum gaskets

To achieve a vacuum seal, a gasket is required. An elastomeric o-ring gasket can be made of buna rubber, viton fluoropolymer, silicon rubber or teflon. O-rings can be placed in a groove or may be used in combination with a centering ring or as a "captured" o-ring that is held in place by separate metal rings. Metal gaskets are used in ultra-high vacuum systems where the outgassing of the elastomer could be a significant gas load. A copper ring gasket is used with conflat flanges. Metal wire gaskets made of copper, gold or indium can be used.

[edit] Vacuum feedthrough

A vacuum feedthrough is a flange that contains a vacuum-tight electrical, physical or mechanical connection to the vacuum chamber. An electrical feedthrough allows voltages to be applied to components under vacuum, for example a filament or heater. An example of a physical feedthrough is a vacuum tight connection for cooling water. A mechanical feedthrough is used for rotation and translation of components under vacuum. A wobble stick is a mechanical feedthrough device that can be used to pick up, move and otherwise manipulate objects in the vacuum chamber.

[edit] See also

[edit] References

  1. ^ KF (QF) Flanges Technical Notes. Kurt J. Lesker Company. Retrieved on 2007-09-02.
  2. ^ a b ISO KF Flanges and Fittings (PDF). Retrieved on 2007-09-02.
  3. ^ CF Flanges Technical Notes. Retrieved on 2007-09-02.
  4. ^ Metal Vacuum Joint, William R. Wheeler, Varian Associates, US patent 3458221
  5. ^ ASA Flanges Technical Notes. Retrieved on 2007-09-02.

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